The present invention relates to a printer containing a frame, a feed roller rotatably supported in the frame for advancing a recording medium, a sheet support plate for supporting the recording medium, a guide rail extending substantially parallel with an axial direction of the feed roller, and a carriage guided at the guide rail and carrying a printhead facing the recording medium on the sheet support plate. The frame is composed of a support structure and two plate-like function blocks which are supported on the support structure at both ends of the feed roller so as to extend in respective planes normal to said axial direction, and which support the guide rail and the sheet support plate.
A related printer is disclosed in U.S. Pat. No. 4,502,796.
A typical example of a printer of this type is an ink jet printer having a printhead or printheads adapted to expel droplets of liquid ink onto the recording medium when the carriage moves along the guide rail to scan the recording medium in a main scanning direction while the recording medium is advanced over the sheet support plate in a sub-scanning direction. The timings at which the nozzles of the printhead are energised must be accurately synchronised with the movement of the carriage relative to the recording medium. To this end, the carriage may be equipped with a detector for reading markings on a ruler. However, in order to achieve a high print quality, it is essential that the feed roller and the sheet support plate, which determine the position of the recording medium, and the guide rail for the carriage are stably and accurately positioned relative to one another. For this reason, conventional printers have a relatively expensive frame structure which is manufactured with high accuracy and provides a sufficient stiffness, especially in view of reaction forces that are caused by the reciprocating scanning movement of the carriage.